A knowledge of the biochemical basis for UV-induced mutagenesis requires an understanding of the interaction of SOS-activated proteins with DNA polymerase at the replication-blocking dipyrimidine lesions. We have suggested previously that the presence of RecA in this multiprotein complex might be an important feature of induced mutagenesis because RecA associates preferentially with UV-irradiat...

Mutations in the p53 tumor suppressor genes in the most common types of skin cancer occur almost exclusively at dipyrimidine sites and are highly characteristic of UVB light. The UVB in sunlight produces cis-syn dimers and (6-4) products at dipyrimidine sites, the latter of which are isomerized by UVA/B light to their Dewar valence isomers. Which of these photoproduct classes is primarily respo...

In the combination of 5-fluorophenyl-1, 3, 7, 9-tetra methylpyrido [2, 3, d, d, 5, 6 dipyrimidine -2, 4, 6, and 8 tetron, there are 4 rings, respectively, ring that is attached to the halogen ring A and, respectively, a ring The lower and the right to the left of the ring A are called C, B, and D. Calculations and studies show that the amount of aromatics in halogen-ring A in all cases has the ...

D-glucose derivatives of dihydropyrido-[2,3-d:6,5-d']-dipyrimidine-2, 4, 6, 8(1H,3H, 5H,7H)-tetraone (GPHs) have been synthesized and investigated as corrosion inhibitors for mild steel in 1M HCl solution using gravimetric, electrochemical, surface, quantum chemical calculations and Monte Carlo simulations methods. The order of inhibition efficiencies is GPH-3 > GPH-2 > GPH-1. The results furth...

We have used a rapid in vivo recombinational method to clone and completely sequence 34 UV-induced mutants at the adenine phosphoribosyltransferase (APRT) locus of Chinese hamster ovary cells. Among the mutants recovered, 26 were single base substitutions including 17 G.C----A.T transitions and a single A.T----G.C transition. Three of the 4 possible transversions accounted for the remaining 8 m...

We examined the spectrum of p53 mutations found in 40 UV-induced skin tumors of xeroderma pigmentosum group A gene (XPA)-deficient mice. p53 mutations were detected in 48% of the tumors. Nearly all of the mutations were induced at dipyrimidine sites. Ninety-three % of the mutations were G.C-->A.T transitions at dipyrimidine sites, including tandem transitions (CC-->TT), which are the hallmark o...

We have examined 35 epidermal tumors induced in mice of four different strains by chronic exposure to ultraviolet B radiation for the presence of aberrations in the p53 tumor suppressor gene. Polymerase chain reaction products from p53 exons 5 to 8 were screened by single-strand conformation polymorphism analysis and sequencing. Base substitutions were found in seven tumors (20%). All mutations...

UV light is considered an important contributor to skin cancer, but methods have been lacking to quantify specific UV-induced lesions in human skin in situ. We applied a newly developed 32P-postlabeling technique to measure specific UV-induced cyclobutane dimers and 6-4 dipyrimidine lesions in the skin of healthy volunteers. At a dose of 400 J/m2, solar-simulated radiation caused at least 20 cy...

Sunlight is a carcinogen to which everyone is exposed. Its UV component is the major epidemiologic risk factor for squamous cell carcinoma of the skin. Of the multiple steps in tumor progression, those that are sunlight-related would be revealed if they contained mutations specific to UV. In a series of New England and Swedish patients, we find that 14/24 (58%) of invasive squamous cell carcino...

The derivatives of fused pyrimidines are valued not only for their rich and varied chemistry, but also for many important biological properties [1 – 3]. Among them, the pyridodipyrimidines (PDP) have been shown to exhibit antibacterial and antiviral properties [4, 5] as well as NAD-type redox catalytic activity [6 – 10]. A few methods are reported in the literature for the preparation of pyrido...